The invention relates to self-expanding cannula, a catheter-sheath, a catheter-sheath-assembly and a method for applying a self-expanding cannula, a catheter-sheath and a catheter-sheath-assembly.
This disclosure provides a means to enable percutaneous access for a cannula, in particular for a cardiac cannula positioned in the heart and/or a major vessel and/or other organs utilized for extracorporeal communication of a fluid. This device provides a conduit communicated between the fluid supply extending outside of the body and provides passage of fluids in and out of the body. The self-expandable cannula in its collapsed or compressed state has a small diameter for introduction and positioning and expands to a relatively large bore conduit for fluid flow.
Medical devices such as cardiac cannulae or other medical devices are typically placed under direct vision into major blood vessels and/or the heart of a patient for the purpose of providing a fluid conduit to and from an extracorporeal circuit.
The most common techniques used in Cardiac Surgery Centers for postcardiotomy support include Extracorporeal Membrane Oxygenation (ECMO) and Ventricular Assist Devices (VAD). Poor ventricular function may be diagnosed preoperatively or may have resulted from myocardial insult during surgery (i.e. inadequate perfusion, crossclamping for extended periods of time limiting reperfusion, injury, etc.). Reduced cardiac output will affect other organs due to low blood pressure and blood flow.
Over time, allowing the myocardium to rest may allow recovery. Otherwise, the patient may require long-term cardiac support. Patients who cannot be weaned from cardiopulmonary bypass and possess isolated ventricular dysfunction are probably candidates for a Ventricular Assist Device (VAD). BiVAD support will require two-pump circuits. When pulmonary dysfunction occurs, the patient is most likely a candidate for ECMO.
Cardiac cannulae provide the patient interface means to an extracorporeal blood circuit. Placement of these cannulae may access the vasculature through major vessels (Right Atrium (RA), Left Atrium (LA), Left Ventricular Apex (LVA), Femoral Artery (FA), Femoral Vein (FV), Superior Vena Cava (SVC), Inferior Vena Cava (IVC) or the Aorta). Two cannulae are required in the extracorporeal circuit—one for blood outflow and one for blood return.
In open chest procedures, the blood inlet (to the pump) cannula is passed through a dilated tunnel created from the ventricle through the subcutaneous plane to the percutaneous access site. The blood return cannula (from the pump) is passed through a dilated tunnel created from the arch of the ascending aorta through the subcutaneous plane to the percutaneous exit site. The percutaneous access sites are located ipsilaterally, on the left abdominal wall for the LVAD, in the medial anterior position. The location is ipsilateral on the right abdominal wall for an RVAD, in the medial anterior position.
The extracorporeal system is attached to the cannulae using good perfusion technique. Cannulae placed within the thorax are typically secured in place to prevent accidental dislodgement which could result in a catastrophic condition. Purse-string sutures and stabilizer grommets often provide security until tissue healing occurs. As such, cannulae removal and/or exchange requires a second surgery under direct visualization. The open chest wound is closed upon successfully administrating the support system.
A problem, which is up to now not yet solved in a satisfactory way, is that the cannulae, which must be introduced into and tunneled through the tissue of the corpus of a patient to get access to the heart, an associate vessel or to an other organ, very often have a comparatively large diameter. Among further things, such a large cannula diameter can affect the skin, tissue or the respective organs to be accessed very negatively and can cause lasting injuries. What is more, it is understood, is that a large cannula diameter complicates and makes the tunneling of the cannula difficult.